A robust and reliable transactional processing is a key quality factor in many database internet information systems. We give three design patterns that model reliable session and transaction management in transactional web applications. These are: session timeout, server default action and split client-server state representation. Only the first design pattern can be successfully implemented with the standard WCF communication facilities available for Silverlight .NET subset. Therefore we include also a simple, robust and WCF compatible communication stack. Surprisingly, overriding the standard WCF facility has resulted in an almost factor 30 performance boost for local calls.